\documentclass{standalone}
\usepackage{tikz}
\usepackage{ctex,siunitx}
\setCJKmainfont{Noto Serif CJK SC}
\usepackage{tkz-euclide}
\usepackage{amsmath}
\usepackage{wasysym}
\usetikzlibrary{patterns, calc}
\usetikzlibrary {decorations.pathmorphing, decorations.pathreplacing, decorations.shapes,}
\begin{document}
\small
\begin{tikzpicture}[>=latex,scale=1]
  \draw[fill=cyan!40!white](90:2)--(210:2)--(-30:2)--cycle;
  % \draw[red,thin,densely dashdotted](150:1.8)--(150:0.2);
  \draw[postaction={decorate},decoration={markings,mark=at position 0.5 with {\arrowreversed{>}}}](150:1.0)--++(-150:2)node[pos=0.8,sloped,above]{白光};
  \draw[densely dashed](150:1.0)--++(30:2);
  \foreach \x[count=\i] in {violet,blue,green,yellow,orange,red}
  {
    \draw[\x,postaction={decorate},decoration={markings,mark=between positions 0.45 and 0.9 step 0.4 with {\arrow{>}}}](150:1)--([shift=(120:1.5+\i*0.1)]-30:2)--([shift=(70:0.75+\i*0.15)]-30:2);
  }
  \draw[ultra thick,gray]([shift=(70:0.6)]-30:2)--++(70:1.4);
  \node at ([shift=(70:0.9)]-30:2)[left=1mm]{紫};
  \node at ([shift=(70:1.65)]-30:2)[above left]{红};
  \node at ([shift=(70:1.35)]-30:2)[right]{黄};
\end{tikzpicture}
\end{document}